[Footnote 3: It is an interesting fact, and one which, as far as I know, has never before been published, that when the practice squadron under Captain (now Rear-Admiral) Luce, sailed in 1865 to Europe, having on board the midshipmen from the Naval Academy, a singular rencontre took place in the English Channel. Meeting an English frigate, Captain Luce hailed from the quarter-deck,-- "Ship ahoy! What ship is that?" "Her Majesty's ship 'President,'" came the answer. "What ship is that?" "The United States ship 'Macedonian,'" replied Captain Luce; for, strangely enough, the two vessels which half a century before had changed sides as prizes in the War of 1812 were now exchanging peaceful greetings under the flags of their respective conquerors.] CHAPTER XIX. THE WAR WITH MEXICO. We now come to a long break of thirty years, during which the United States were at peace with all the nations of the earth. But in this period the navy was by no means idle. There was first a long and arduous campaign against the pirates of the West Indies, which ended at last in sweeping from the seas the gangs of cut-throats that had so long infested the Spanish Main. When this important work had been successfully accomplished, the navy was actively occupied in putting down the slave trade on the coast of Africa, and in protecting American commerce from the depredations of savage tribes in distant countries, above all on the coasts and islands of the Pacific and the Indian Oceans. The navy too was busy with its peaceful occupations; for as the co-adjutor of the nation's commerce it is a part of its duty to survey and explore the waters upon coasts hitherto unknown, to map out the channels, and to warn against the rocks and shoals and other dangers to the ships that will some day have to navigate these remote seas. It was in this period that the great exploring expedition was sent out to the Pacific under Lieutenant Wilkes, whose researches gave us our first accurate knowledge of the waters of this region, and form a lasting monument to the memory of the commander, and to the zeal and energy and skill of the navy which planned and carried out the enterprise.